Health Guide
Drug Guide

Barbiturate (Oral route, parenteral route, rectal route)

Brand Names:

Dosage Forms:

Uses of This Medicine:

Barbiturates belong to the group of medicines called central nervous system (CNS) depressants (medicines that cause drowsiness). They act on the brain and CNS to produce effects that may be helpful or harmful. This depends on the individual patient's condition and response and the amount of medicine taken.

Some of the barbiturates may be used before surgery to relieve anxiety or tension. In addition, some of the barbiturates are used as anticonvulsants to help control seizures in certain disorders or diseases, such as epilepsy. Barbiturates may also be used for other conditions as determined by your doctor.

The barbiturates have been used to treat insomnia (trouble in sleeping); but if they are used regularly (for example, every day) for insomnia, they are usually not effective for longer than 2 weeks. The barbiturates have also been used to relieve nervousness or restlessness during the daytime. However, the barbiturates have generally been replaced by safer medicines for the treatment of insomnia and daytime nervousness or tension.

If too much of a barbiturate is used, it may become habit-forming.

Barbiturates should not be used for anxiety or tension caused by the stress of everyday life.

These medicines are available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, phenobarbital is used in certain patients with the following medical condition:

Before Using This Medicine:


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Unusual excitement may be more likely to occur in children, who are usually more sensitive than adults to the effects of barbiturates.

Older adults

Confusion, mental depression, and unusual excitement may be more likely to occur in the elderly, who are usually more sensitive than younger adults to the effects of barbiturates.


Barbiturates have been shown to increase the chance of birth defects in humans. However, this medicine may be needed in serious diseases or other situations that threaten the mother's life. Be sure you have discussed this and the following information with your doctor:


Barbiturates pass into the breast milk and may cause drowsiness, slow heartbeat, shortness of breath, or troubled breathing in babies of nursing mothers taking this medicine.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

For patients taking the extended-release capsule or tablet form of this medicine:

For patients using the rectal suppository form of this medicine:

Use this medicine only as directed by your doctor. Do not use more of it, do not use it more often, and do not use it for a longer time than your doctor ordered. If too much is used, it may become habit-forming (causing mental or physical dependence).

If you think this medicine is not working properly after you have taken it for a few weeks, do not increase the dose. To do so may increase the chance of your becoming dependent on the medicine. Instead, check with your doctor.

If you are taking this medicine for epilepsy, it must be taken every day in regularly spaced doses as ordered by your doctor in order for it to control your seizures. This is necessary to keep a constant amount of medicine in the blood. To help keep the amount constant, do not miss any doses.


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Store the suppository form of this medicine in the refrigerator.

Precautions While Using This Medicine:

If you will be using this medicine regularly for a long time:

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine .

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of the metyrapone test may be affected by this medicine.

If you have been using this medicine for a long time and you think that you may have become mentally or physically dependent on it, check with your doctor. Some signs of mental or physical dependence on barbiturates are:

If you think you or someone else may have taken an overdose of this medicine, get emergency help at once. Taking an overdose of a barbiturate or taking alcohol or other CNS depressants with the barbiturate may lead to unconsciousness and possibly death. Some signs of an overdose are severe drowsiness, severe confusion, severe weakness, shortness of breath or slow or troubled breathing, slurred speech, staggering, and slow heartbeat.

This medicine may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert .

Oral contraceptives (birth control pills) containing estrogen may not work properly if you take them while you are taking barbiturates. Unplanned pregnancies may occur. You should use a different or additional means of birth control while you are taking barbiturates. If you have any questions about this, check with your health care professional.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Bleeding sores on lips
chest pain
muscle or joint pain
red, thickened, or scaly skin
skin rash or hives
sores, ulcers, or white spots in mouth (painful)
sore throat and/or fever
swelling of eyelids, face, or lips
wheezing or tightness in chest

Check with your doctor as soon as possible if any of the following side effects occur:

Less common
mental depression
unusual excitement
Hallucinations (seeing, hearing, or feeling things that are not there)
unusual bleeding or bruising
unusual tiredness or weakness
With long-term or chronic use
Bone pain, tenderness, or aching
loss of appetite
muscle weakness
weight loss (unusual)
yellow eyes or skin
Symptoms of overdose
Confusion (severe)
decrease in or loss of reflexes
drowsiness (severe)
irritability (continuing)
low body temperature
poor judgment
shortness of breath or slow or troubled breathing
slow heartbeat
slurred speech
trouble in sleeping
unusual movements of the eyes
weakness (severe)

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
Clumsiness or unsteadiness
dizziness or lightheadedness
"hangover" effect
Less common
Anxiety or nervousness
feeling faint
nausea or vomiting
nightmares or trouble in sleeping

Confusion, mental depression, and unusual excitement may be more likely to occur in very ill patients.

After you stop using this medicine, your body may need time to adjust. If you took this medicine in high doses or for a long time, this may take up to about 15 days. During this period of time check with your doctor if any of the following side effects occur (usually occur within 8 to 16 hours after medicine is stopped):

Anxiety or restlessness
convulsions (seizures)
dizziness or lightheadedness
feeling faint
hallucinations (seeing, hearing, or feeling things that are not there)
muscle twitching
nausea or vomiting
trembling of hands
trouble in sleeping, increased dreaming, or nightmares
vision problems

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 10/12/2016

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